Decreasing the phenolic content of liquids by an electrochemical technique

ABSTRACT

A METHOD FOR DECREASING THE PHENOLIC CONTENT OF A SOLUTION WHICH COMPRISES PASSING AN ELECTRIC CURRENT THROUGH A SOLUTION CONTAINING PHENOLIC MATERIAL, WHICH SOLUTION IS CONTAINED AS THE ELECTROLYTE IN A CELL, SAID CELL HAVING AT LEAST ONE POSITIVE AND ONE NEGATIVE ELECTRODE, BETWEEN WHICH THE CURRENT IS PASSED, AND WHEREIN THE ELECTROLYTE ALSO CONTAINS A BED OF PARTICLES, DISTRIBUTED THEREIN, SUCH THAT THE POROSITY OF THE BED IS FROM ABOUT 40 TO 80%, POROSITY BEING DEFINED AS   THE ELECTROLYSIS OF THE ELECTROLYTE IS CONTINUED UNTIL THE DESIRED REDUCTION IN THE PHENOLIC CONTENT THEREOF IS OBTAINED.

May 1, 1973 TARJANYI ET AL 3,730,864

' DECREASING THE PHENOLIC CONTENT OF LIQUIDS BY AN ELECTROCHEMICALTECHNIQUE Filed April 14, 1971 United States Patent Filed Apr. 14, 1971,Ser. No. 133,918 Int. Cl. B01k 3/00; C02c 5/12 US. Cl. 204-149 15 ClaimsABSTRACT OF THE DISCLOSURE The electrolysis of the electrolyte iscontinued until the desired reduction in the phenolic content thereof isobtained.

Volume of particles Volume of cell wherein the) X 100 particles aredistributed This invention relates to a process for treating solutionswhich contain phenolic materials and more particularly it relates to animproved electrochemical process for decreasing the phenolic content ofa solution.

In various industries which utilize phenolic materials, such as themetal plating industry, the phenol-formaldehyde resin industry, steelmills, oil refineries, and the like, the phenolic material eflluent fromthese industrial processes poses a significant pollution problem.Although heretofore, various chemical techniques have been proposed forthe treatment of such phenolic containing efiluents, these havegenerally been either ineflicient or too expensive or have resulted inthe formation of products whose disposal presents as many pollutionproblems as the phenolic materials themselves. Accordingly, there hasrecently been a great deal of etfort expended in the development of newand diiferent processes for the treatment of these phenolic containingefiluent solutions.

In Belgium Pat. 739,684, for eXample, there is described anelectrochemical technique wherein a semi-conductive bed of solidparticles is used to oxidize various substances to non-toxic forms.Another process, utilizing an electrochemical technique for removingphenol is described in New Scientist, June 26, 1969, page 706. In theseand similar processes which have recently been proposed, theelectrochemical systems utilized have been found to be both ineificient,and/or uneconomical and require frequent changing of the bed ofparticles which is utilized. Accordingly, these systems have not metwith any appreciable commercial utilization.

It is, therefore, an object of the present invention to provide animproved process for treating solutions containing phenolic materials soas to reduce the phenolic content of such solutions.

A further object of the present invention is to provide an improvedprocess for reducing the phenolic content of a solution by means of anefficient and economical electrochemical treatment.

These and other objects will become apparent to those skilled in the artfrom the description of the invention which follows.

Pursuant to the above objects, the present invention includes a processfor treating a solution containing phenolic materials to decrease thephenolic content thereof which comprises passing an electric currentthrough the solution which contains the phenolic materials, whichsolution is contained as the electrolyte in a cell, said cell having atleast one positive and one negative electrode, between which the currentis passed, and wherein the electrolyte also contains a bed of particles,distributed therein such that the porosity of the bed is from about 40to porosity being defined as Volume of particles By carrying out theelectrochemical treatment of the solutions containing phenolic materialsin this manner, it has been found to be possible to reduce theconcentrations of these phenolics in the solutions from the parts permillion level to the parts per billion level.

More specifically, in the practice of the method of the presentinvention, the solutions which are electrolyzed to effect the reductionin the phenolic content thereof, i.e., the electrolyte solutions in thecell, may be various solutions which contain phenolic materialsalthough, preferably, these are aqueous solutions. These solutions maycontain varying amounts of the phenolic materials, solutions containingas much as 10% by Weight and as little as one part per million of thephenolic material being suitable for treatment in accordance with theprocess of the present invention to etfect a reduction of the phenoliccontent. In referring to the phenolic material in the solutions, it isintended to include not only phenol itself, i.e. C H OH, but alsochlorinated phenols, such as mono-, di-, and trichlorophenol, as well asvarious alkyl substituted phenols, such as 3,4,5-trimethyl phenol, andother chemical compounds in which there is present a phenyl ring with anhydroxyl group attached thereto. Additionally, since it is believed thatthe phenolic materials are removed from the solutions treated by thepresent process by means of oxidation, phenol going through variousoxidation states and resulting ultimately in carbon dioxide, thesolutions treated may also contain various oxidized states of phenol andother phenolic materials, such as maleic acid, quinone, and in itsreduced form, hydroquinone and the like.

The solutions containing phenolic materials which are to be treated inaccordance with the present method may come from various sources. Thus,for example, they may be effluent streams from industrial plants whichhave relatively high concentrations of the phenolic materials.Additionally, however, the solutions treated may have a relatively lowconcentration of phenolic materials, e.g. one part per million or less,which solutions may come from municipal or other water treating plants.Thus, the method of the present invention may be used not only to reducethe relatively high content of phenolic materials in industrial andsimilar waste streams, but, additionally, may also be used to eifectsubstantially complete removal of relatively small amounts of phenolicmaterials, as a final purification step in the treatment of waterintended for human consumption. In the latter instance, this finalpurification may be effected on either a large scale, e.g. at themunicipal water treatiing plants, or on a smaller scale, e.g., in thehomes of the ultimate water consumer. In the case of industrial wastesolutions, these solutions may also contain various other components, inaddition to the phenolic materials, such as mixed efiluent streams fromseveral different industrial processes. Thus, for example, solutionscontaining, in addition to the phenolic materials, various chloridematerials, such as chlorinated organics, chlorine, HCl, hypochlorites,hypochlorous acid, and the like, may be successfully treated by theprocess of the present invention. Such chloride containing solutionsare, however, merely exemplary of the mixed waste effiuent solutionswhich may be treated.

The pH of the solution to be treated may vary over a wide range, beingeither acidic, neutral or basic, pH values of from about 1 to 14 havingbeen found to be suitable. In the preferred operation of the presentprocess, however, and particularly where reduction in the content ofphenolic materials into the parts per billion range is desired, pHvalues on the basic side, e.g. from about 8 to 14, have been found to beadvantageous, with a pH range of from about 9 to 13 being particularlypreferred. Depending upon the makeup of the phenolic-containing solutionwhich is to be treated, adjustment of the pH may be done by the additionof various support electrolytes to the phenolic solution. Suitablesupport electrolytes which may be used are aqueous solutions of borates,ammonia, sodium chloride, sulfuric acid, calcium chloride, sodiumcyanide, chloroacetates, sodium hydroxide, sodium bicarbonate,hydrochloric acid, and the like.

The temperature of the electrolyte, i.e., the solution being treated,may also vary over a wide range, the only criteria being that at thetemperature used, the electrolyte remain a liquid. Thus, temperatureswithin the range of about to 100 degrees centrigrade have been found,generally, to be suitable. For economy in operation, however, it hasfrequently been found to be preferred to utilize these solutions atambient temperatures. Similarly, the present process is desirablycarried out at atmospheric pressure although either subor superatmospheric pressures may be employed, if desired. -It has been found insome instances, however, that the use of elevated temperatures, e.g.,(SO-70 C., may be desirable in effecting a more rapid reduction in thephenolic content, depending upon the particular support electrolyte, pHrange, type and concentration of phenolic which are used.

As has been noted hereinabove, the electrolyte, i.e., the solution beingtreated, is contained, during treatment, in a suitable electrolytic celland contains a bed of particles which are distributed in the electrolytein the cell, such that the porosity of the bed ranges from about 40 to80%,

porosity being defined as:

( Volume of cell wherein the) X 100 particles are distributed Bydetermining the density of the particles used and weighing them, theterm volume of the particles in the above porosity formula may bereplaced by the value for the weight of the particles divided by thetrue density of the particles. The particle density can be measured byfilling a one liter container with particles, the weight of which isknown. Then, an electrolyte is added to the container to fill the voidsbetween the particles, the amount of electrolyte needed being measuredas it is added. The true density of the particles, in grams per cm. isthe weight of the particles in grams divided by the true volume of theparticles in cm. The true volume of the particles is the bulk volumeminus the volume of the voids in the particle bed, the latter being thevolume of the electrolyte which is added to the one liter container.Thus, the true volume of the particles in this instance would be 1000cubic centimeters minus the volume of the voids, i.e., the volume ofelectrolyte added to the container.

It will, of course, be apparent that the porosity of the bed ofparticles maintained in the electrolyte which is being treated in thecell may be varied and that with different types of particles, under thesame operating conditions or with similar particles under differentoperating conditions, changes in the bed porosity will take place. Thus,the true density of the particle will vary depending upon the porosityof the particles themselves, e.g., graphite as compared to glass beads,with similar variations in den- Volume of particles sity being effectedby the electrolyte itself because of the differences in the surfacetension of various electrolyte solutions. Additionally, since theparticles of the bed are generally dispersed or distributed by the flowof the electrolyte through the cell, variations in the fiowcharacteristics will also result in changes in the bed porosity.

To illustrate this latter situation, if a one liter container werefilled with particles of a particular size and shape, using the formulagiven above, the porosity of this bed of particles would be:

( Volume of particles in cc.

If the same quantity of particles were then distributed by the flow ofthe electrolyte, such that the volume of the bed now reached two liters,using its same formula, the porosity of the bed is now Volume ofparticles in cc.

Clearly, in the second instance, the porosity of the bed has increased.As has been noted above, the porosity of the bed of particles dispersedin the electrolyte may range from about 40 to In many instances, apreferred range for the bed porosity is from about 55 to 75% with aspecifically preferred range being from about 60% to 70%.

The particles employed to form the porous bed in the present processtypically are solid, particulate materials that may be conductive,non-conductive or semi-conductive. By conductive it is meant that thematerial of which the particles are made will normally be considered anelectron-conducting material. Where the particles are conductive, theymay have a metallic surface, either by virtue of the particlesthemselves being metallic or by being made of non-conductive material onwhich a metallic surface has been deposited. Typical of the metals whichmay be employed are the metals of Group VIII of the Periodic Table, suchas ruthenium and platinum, as well as other conductive elements, such asgraphite, copper, silver, zinc, and the like. Additionally, theconductive particles may be electrically conductive metal compounds,such as ferrophosphorus, the carbides, borides or nitrides of variousmetals such as tantalum, titanium, and zirconium, or they may be variouselectrically conductive metal oxides, such as lead dioxide, rutheniumdioxide, and the like. Where the particles are non-conductive, they maybe made of various materials, such as glass, Teflon coated glass,polystyrene spheres, sand, various plastic spheres and chips, and thelike. Exemplary of various semi-conductive materials of which theparticles may be made are fly ash, oxidized ferrophos, zirconia,alumina, conductive glasses, and the like.

The particles used desirably range in size from about 5 to 5000 microns,with particle sizes of from about 50 to 2000 microns being preferred. Inmany instances, a particularly preferred range of particle sizes hasbeen found to be from about to 800 microns. Although it is not essentialto the successful operation of the process of the present invention thatall of the particles in the porous bed distributed in the electrolytehave the same size, for the most preferred operation of the process, ithas been found to be desirable if the range of particle sizes ismaintained as small as is practical.

It has further found that the density of the particles used should besuch, that in conjunction with the size and shape of the particles, itwill provide the proper balance between the drag force created by theelectrolyte motion and the buoyancy and gravitational forces required toachieve particle dispersion or distribution at the desired bed porosity.Thus, where the particle dispersion is established against or inopposition to the buoyancy force, the particle densities typically mayrange from about 0.1 (less than the density of the electrolyte) to about1.0 gram per cc. Where the particle dispersion is achieved against or inopposition to the gravitational force, the particle densities typicallymay range from about 1.1 to grams per cc. and preferably from about 1.5to 3.5 grams per cc. The most preferred operating conditions have beenfound to be when the particles are dispersed throughout the electrolyte,Within the cell, during the movement of the electrolyte and when theparticles are more dense than the electrolyte.

The electrolytic cell may be of any suitable material and configuratiolnwhich will permit electrolysis of the phenolic containing solution toeffect a reduction in its phenolic content and which will permitretention of the porous bed of particles in the electrolyte, within thecell. Exemplary of suitable materials of construction which may be usedfor the cell are various plastics, such as the polyacrylates,polymethacrylates, polytetrahaloethylenes, polypropylenes, and the like,rubber, as well as materials conventionally used in the construction ofchlor-alkali cells such as concretes. Additionally, the cells may bemade of metal, such as iron or steel. In such instances, electricallyinsulating coatings should be provided on the metal surfaces in the cellinterior or electrical insulation provided between the metal of the celland the electrodes. The size of the electrolytic cell may also varywidely, depending upon the nature and quantity of the phenoliccontaining solution which is to be treated. Thus, where appreciablequantities are involved, as in the treatment of industrial wastes or asa part of a water purification system, the cell may be relatively largeand include a multiplicity of treating zones, whereas for the treatmentof water for individual home use, appreciably smaller units may beutilized, similar in size to conventional soft-water treating units.Additionally, the cell may be of a suitable size so as to be portable,for use at camp sites, and the like. Typically, the cell will have asuitable inlet and outlet means for introducing and removing the solution to be treated, means for retaining the porous bed of particlesdispersed in the electrolyte within the cell and means for supporting atleast one positive and one negative electrode in contact with theelectrolyte in which the porous bed of particles is distributed.

The electrolytic cell has within it at least one positive and onenegative electrode. These are disposed within the cell so as to be incontact with the electrolyte in which is distributed the porous bed ofparticulate material. These electrodes may be formed of variousmaterials, as are known to those in the art. Typical of suitableelectrode materials which may be used are graphite; noble metals andtheir alloys, such as platinum, iridium, ruthenium dioxide, and thelike, both as such and as deposits on a base metal such as titanium,tantalum, and the like; conductive compounds such as lead dioxide,manganese di oxide, and the like; metals, such as cobalt, nickel,copper, tu ngsten bronzes, and the like; and refractory metal compounds,such as the nitrides and borides of tantalum, titanium, zirconium, andthe like.

The positive and negative electrodes will be positioned within theelectrolytic cell so as to be separated sufliciently to permit the flowof the electrolyte through the cell and the movement of the particlewithin the electrolyte. It will be appreciated, of course, that as theseparation between the electrodes is increased, the voltage necessary toeffect the desired reduction in the phenolic content of the electrolytewill also increase. Accordingly, in many instances it has been found tobe desirable if the separation between the positive and negativeelectrode in the cell is from about 0.1 to 5.0 centimeters, with aseparation of from about 0.3 to about 3.0 centimeters being preferredand a separation of from about 0.5 to 2.0 centimeters being particularlypreferred. Although particular reference has been made to anelectrolytic cell having one positive and one negative electrode, itwill be appreciated that the cell may be provided with a plurality ofelectrode pairs,

in much the same manner that such a plurality of electrodes are normallyutilized in various commercial, large scale electrolytic continuousprocesses.

It will, of course, be appreciated that in addition to the amount ofelectrode separation, the flow of the electrolyte through the electrodearea will also be dependent upon the size and density of the particleswhich are distributed in the electrolyte to form the porous bed.Typically, this flow, which is described in terms of the linear flowvelocity of the electrolyte, will be within the range of from about 0.1to 1000 centimeters per second. A preferred electrolyte flow velocityhas been found to be from about 0.5 to centimeters per second with aflow velocity of from about 1 to 10 centimeters per second beingspecifically preferred. Under these operating conditions, currentdensities within the range of about 1.0 to 500 milliamps per square inchhave been found to be typical of those which are utilized.

To further illustrate the present invention, reference is made to theaccompanying drawing which is a schematic diagram of a systemincorporating the electrolytic cell of the invention. As shown in thedrawing, this system includes an electrolytic cell 1 having a fluidinlet 6 and a fluid outlet 9. Within the cell 1 are disposed a positiveelectrode 2 and a negative, electrode 3. Although these electrodes areshown as being separated by a diaphragm 4, in many instances, the use ofsuch a diaphragm has not been found to be necessary. Where such adiaphragm is used, e.g., to control the particles in the anolyte orcatholyte compartments, the diaphragm may be formed of variousmaterials, such as a Teflon coated screen. An electrolyte 8 is providedwithin the cell, which electrolyte is a solution containing phenolicmaterial. A source 5 of this electrolyte is provided, from which theelectrolytes may be introduced into the cell through the inlet 6.Distributed within the electrolyte 8 are particles 7, which particlesare distributed randomly through the electrolyte, the nature of thedistribution depending upon the electrolyte flow, size and density ofthe particles, density of the electrolyte, and the like. The electrolyte8 is pumped into the cell 1 through the inlet 6 from the electrolytesource 5 and exits from the cell through the outlet 9 for recirculationthrough line 12 or for subsequent processing through line 13, as isdesired. The cell is further provided with screens 10 and 11, screen 11serving to support the particles in the cell and screen 10 serving tomaintain the particles within the cell and prevent their dischargethrough the outlet 9. As the distance between the screens 10 and 11 ischanged, the volume of that portion of the cell in which the particlesare distributed will likewise vary, thus, varying the porosity of thebed of particles which is maintained within the cell.

While it is not intended to restrict the operability of the presentinvention by any theory of operation, the use of particles in anelectrolytic cell in the manner which has been described, has been foundto have the following advantages. In a conventional electrolytic cell,such as a chlor-allkali cell, the amount of electrode surface at whichthe electrolytic reaction is conducted is dependent upon the surfacearea of the electrodes. Typically, this surface area will be about 1.3time 10 cm. With a typical cell volume of about 3.5 times 10 cm. theresulting ratio of the electrode area per cell volume is about 0.037 cm./cm. By the use of conductive particles in an electrolytic reaction, asin the process of the present invention, there is a significant increasein the surface area at which the electrolytic reaction may occur. InChemical and Process Engineering, February 1968, page 93, there isdescribed a cell containing an electrolyte having particles therein. Itwas calculated that the electrolyte containing the particles has anelectrode area of about 11,500 cm. and that the volume of the cell isabout 153 cm. This gives a ratio of electrode area to cell volume ofabout 75 cm. /cm. which, clearly, is significantly higher than that ofan electrolytic cell having conventional electrodes.

Additionally, it is believed that by the use of the particles in theelectrochemical reaction, a mass transport phenomena may be takingplace. In this, the contact of phenolic materials with the particles andelectrodes is dependent upon a number of variables, including the elec-8 EXAMPLE 8 The procedure of Example 7 was repeated with the exceptionthat the phenol-containing solution was an organic efiluent containing2,4,5-trichlorophenol and having an initial phenol content of 3.0parts/million. The trolyte flow a the Pamela t denshty and type andparticles were graphite, having a size of about 177 mithe concentrationof the phenolic material. From a concrons the anode was graphite thecathode was nickel and sideration of all of the above variables, it hasbeen found the Sparafion between themwas 2 1 cm The flowiate that h oneconqifion which has an T' upon an through the apparatus was adjusted toprovide a porosity them s the goosltyhof the bed of ilartlcles and thatthis in the bed of particles of 80%. The phenoi containing porosity, ase ned erelnabove,1 st e determining f f solution, at an initial pH of8.7, was electrolyzed for that makes possible a commercially feaslbleoperatlon. 60 minutes using a current of O 804) 90 amp and a vow Inorder that those skilled in the art may better underage of 50 volts Atthe end of'this t'ime the PH of the stand the presfnt mventlon themtmner m which M solution was 5.2 and the phenol content was 0.140 part/may be practiced, the following speclfic examples are 5 miniom given. Inthese examples, unless otherwise indicated, tem- EXAMPLE peratures arein degrees centigrade and parts and percent are by weight. It is to beappreciated, however, that these procedul'e 0f E p 3 Was repeatfid h theexamples are merely exemplary of the present invention {Xceptloh thatthe paftlcles Used Weft? feffophos havlhg a and the manner in which itmay be practiced and are not E of 8 9 hllcrons' After elcctmlyhlng the Fto b taken as a limitation thereoh tron, having an lnltlal pH of 8.8,for 60 mmutes using a I the f ll i examples, 700 milliliters of anacluecurrent of 2.1-2.8 amps and a voltage of 10.0 volts, the ous phenolsolution, containing 1000 parts per million PH and the PhenQ1 Contentwas 0-100 Parts/ phenol was used for each example. The phenol solutionmllhonwas circulated through apparatus similar to that shown EXAMPLE inthe drawing for 15 minutes to allow for equilibration. The procgdu -e fExample .5 was repeated with the A 5o'mllhhtel" Sample was thenWithdrawn and h y exception that the particles used were glass beadshaving for Ph content- The analyses Showed substahtlally a particle sizeof 500 microns. The support electrolyte h h Q l Phenol content of 1000Parts was a 0.3 M NaCl solution, added in an amount to make PF mllhoh,lhdlcatlhg httle it y absorptloh 011 the p the solution pH 4.65. Thesolution was electrolyzed for trcles or electrodes in the cell. Thephenol solution was 11 hours at a current f 1,0 amp d an average l thenelectrolyzed under the conditions indicated in the age of 336 volts,using a fl t which provided a bed following table. The electrolyte wasthen drained from porosity f 5% At h end f this time, the phenol theapparatus and agam analyzed for phenol Content All content of thesolution was found to be reduced from Phenol analyses were done y gasChromatographic techthe initial 1000 parts/million to 0.52 part/million.nique. The olf gases from the cell were collected by the l downwarddisplacement of water and carbon dioxide was EXAMPLE 11 measured byinfrared analysis. In these examples, there The procedure of Example 10was repeated with the was no diaphragm used in the cell, the particleswere exception that the phenol content of the solution treated graph1te,having a particle size of from 596840 microns, was 1145 parts/ million.The electrolysis was effected for the anode was graph1te, the cathodewas nickel and the a period of 19.5 hours at a. current of 1 amp, avoltage separation between the anode and cathode was 0.5 centiof 4.855.4volts and an anode separation of 0.65 centimeter. The electrolyte fiowrate was adjusted during the meter. The solution flow rate was such asto establish electrolysis so as to have a porosity of the bed ofgraphite a bed porosity of At the end of this time, the phe- 45particles of from 63-74%. Additionally, various supnol concentration wasfound to be 0.002 part/million. port electrolyte solutions were added tothe phenol solu- While there have been described various embodimentstion to adjust the pH to the values shown. Using this proof theinvention, the compositions and methods described cedure, the followingresults were obtained: are not intended to be understood as limiting thescope Total elee- Total P.p.m' trolysis Cell Cell amp- Cell gas phenolEleetrotime current voltage hours evolved after elec- Ex.Supporteleetl'olyte added lyte pH (hours) (amps) (volts) passed (00.)trolysls 0.1M N b t l t 9.7 3.5 0.6 3.8-4 2.1 500 420 1 .1 Mz ife i i sa g i l l lt h 10 5% 0.6 4.24.9 3.2 500 400 .1 M aqueousNaboratesolutioneontai ug 10.2 4 0.6 2.9-3.8 2.4 470 430 .1 M aqueoussulfuric acid solution 1. 1 3% 0.6 1.9-2. 9 2.2 600 400 .1 M aqueous Naborate solution 9. 7 2 0. 6 H. 2 1. 2 600 560 6 5.0% aqueous sodiumchloride solution 5.7 20% 0.6 2. 85-3.4 14.4 1,000 10 EXAMPLE 7 of theinvention, as it is realized that changes therewithiu o n a n h 1 Theprocedure of the preceding examples was repeated are.poss.lble and It 13further. mtenqed h t eac e ement u recited in any of the followingclaims is intended to be with the exception that no support electrolytewas used,

understood as referring to all equivalent elements for thephenol-contalmng solutlon treated was an effluent bt ti H th m result insubstam from phenol-formaldehyde processing which initially con- Z i? mgSu 5 an i m 6 c it bein intended tained 900 parts/million phenol and theparticles were 65 y i q g P f rim graphite with 1% by weight palladiumdeposited thereon, 9 fever 3 ma y m w a ever 0 m 1 s p which particleswere about 2000 microns in size. The g $1 3 anode in the cell wasgraphite, the cathode was nickel 1 Z Is i a th h u f and the spacebetween them was 2.1 cm. The flow rate 1 me for ecfeasmg P c cofltent oa of the solution was adjusted so as to provide a porosity so which.compnsfasl Passlng l f in the bed of particles of 65%. This electrolyzedfor 60 throhgh a soluhqn contammg a phenohc materlal, w minutes at acurl-em f amps and a voltage f solution is contained as the electrolyteIn a cell, said cell 5.0 volts. At the end of this time, analysis of thesolution havmg at lehst one posmve one nesahve ekqwde showed a reductionin the phenol content from the initial between Whwh the current 15passed, a h the 900 parts/million to 5 parts/million. electrolyte alggcontains a bed of particles, dlstrlbuted therein such that the porosityof the bed is from about 40 to 80%, porosity being defined as Volume ofparticles 2. The method as claimed in claim 1 wherein the electrolytesolution is an aqueous solution.

3. The method as claimed in claim 2 wherein the initial concentration ofthe phenolic material in the electrolyte solution is from about 1 partper million to by weight.

4. The method as claimed in claim 1 wherein the particles distributed inthe electrolyte solution have a density which is greater than that ofthe electrolyte.

5. The method as claimed in claim 1 wherein the particles distributed inthe electrolyte solution are conductive particles.

6. The method as claimed in claim 5 wherein the particles are graphite.

7. The method as claimed in claim 5 wherein the particles have ametallic surface.

8. The method as claimed in claim 5 wherein the particles are leaddioxide.

9. The method as claimed in claim 1 wherein the particles aredistributed within the electrolyte by flowing the electrolyte throughthe electrolytic cell in a direction opposed to the gravitationalforces.

10. The method as claimed in claim 9 wherein the electrolyte flo-wvelocity through the cell is from about 0.1 to 1000 centimeters persecond.

11. The method as claimed in claim 1 wherein the electrolyte solutionhas a pH of from about 8 to 14.

12. The method as claimed in claim 1 wherein the porosity of the bed ofparticles is from about to 75%.

13. The method as claimed in claim 12 wherein the porosity of the bed ofparticles is from about to 14. The method as claimed in claim 1 whereinthe separation between the positive and negative electrode within thecell is from about 0.1 to 5.0 centimeters.

15. The method as claimed in claim 1 wherein the electrolyte solutionalso contains chloride ions.

References Cited UNITED STATES PATENTS 698,292 4/1902 Kendall 204-1 103,457,152 7/1969 Maloney, Jr. et al. 204- X 3,616,356 10/1971 Roy204-152 FOREIGN PATENTS 1,584,158 12/1969 France 204-Dig. 10

OTHER REFERENCES Le Goff et al.: Applications of Fluidized Beds inElectrochem, Indust. & Eng. Chem., vol. 61, No. 10, October 1969, pp.8-17.

JOHN H. MACK, Primary Examiner A. C. PRESCOTT, Assistant Examiner US.Cl. X.R.

204-130, Dig. 10, 72

